This invention relates generally to devices for converting wind forces into usable energy and more particularly to a vertical axis wind turbine for this purpose.
The technology developed for converting wind forces into work energy is well known. For example, devices such as wind mills are evidence of the long standing recognition that it is possible to harness wind forces to perform tasks requiring energy output as well as to gather and store energy thus developed.
A particular construction for such purposes hereinafter referred to as a wind turbine or wind motor is disclosed in U.S. Pat. No. 1,697,574 to Savonius. The Savonius device comprises a rotor disposed on a vertical axis which has complementary vertically and longitudinally extending elements rotatable about individual axes to define in horizontal cross-section an essentially S-shaped configuration. This device known as the "S-rotor," resembles the cylindrical rotor of Professor Gustav Magnus and is distinguishable in that the oppositely arranged complementary vanes overlap to define between them centrally S-shaped air passage of constant area which Savonius found enhanced the speed and torque developed by the rotor. Among its advantages, the Savonius S-rotor was operable in response to any wind movement, regardless of direction.
In a further U.S. Pat. No. 1,766,765 Savonius provides an improved vertical axis wind turbine wherein he makes provision for speed control means comprising movable flaps located in transverse relation on the complementary vanes to reduce the speed of rotation of the rotor member during excessive wind movement and velocities.
In U.S. Pat. No. 2,596,726 to Rydell another vertical axis type wind turbine is shown having telescoping and complementary semi-cylindrical elements which are respectively curved and capable of lateral displacement with respect to each other to define the S-shaped rotor in operation. Rydell relies on a rack and pinion linkage for the lateral adjustment of his vanes.
U.S. Pat. No. 3,093,194 to Rusconi also relates to a vertically disposed wind motor having a plurality of vertically disposed curved air foils which are pivotally linked with respect to each other to define in one configuration an approximate S-shaped rotor. Rusconi controls the speed and energy developed by his device by coiled torsion springs for resisting the relative outward movement of the respective vanes during operation of the device. The spring tends to bring the blades into a configuration promoting the S-shape which optimizes operation of the device.
Finally, U.S. Pat. No. 3,942,909 to Yengst discloses a vertical axis wind driven rotor having hinged vanes which rotate on individual axes to move from the closed position in which they form a cylinder to an open position defining the S-shaped rotor similar to Savonius.
All of the above devices possess certain drawbacks, in that they tend to be erratic in operation and subject to undesirable variations in torque and energy output. Further, the devices of Savonius and Rydell are intended for reversible operation applicable primarily for the propulsion of ships, and were thus less concerned with the type of uniformity of torque and rotation which has been found desirable in the instance where the devices of this type are to be applied for the purpose of harnessing wind currents to produce energy and to perform specific work tasks.
Finally, all of the foregoing devices have relatively complex construction which is expensive to assemble and maintain.
The present invention overcomes the problem of these prior art devices by providing a wind turbine which has a substantially consistent uniform output in an environment of constantly varying wind forces and speeds, and includes means to avoid damage to the device resulting from excessive rotating during periods of extreme wind forces and velocities as occurs during wind storms and the like.